/**
 *  Copyright (c) 1997-2013, www.tinygroup.org (luo_guo@icloud.com).
 *
 *  Licensed under the GPL, Version 3.0 (the "License");
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *       http://www.gnu.org/licenses/gpl.html
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */
package org.tinygroup.jspengine.compiler;

import org.tinygroup.jspengine.JasperException;
import org.tinygroup.jspengine.JspCompilationContext;
import org.tinygroup.jspengine.org.apache.commons.logging.Log;
import org.tinygroup.jspengine.org.apache.commons.logging.LogFactory;

import java.io.CharArrayWriter;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.Vector;
import java.util.jar.JarFile;

/**
 * JspReader is an input buffer for the JSP parser. It should allow
 * unlimited lookahead and pushback. It also has a bunch of parsing
 * utility methods for understanding htmlesque thingies.
 *
 * @author Anil K. Vijendran
 * @author Anselm Baird-Smith
 * @author Harish Prabandham
 * @author Rajiv Mordani
 * @author Mandar Raje
 * @author Danno Ferrin
 * @author Kin-man Chung
 * @author Shawn Bayern
 * @author Mark Roth
 */

class JspReader {

    // Logger
    private static Log log = LogFactory.getLog(JspReader.class);

    private Mark current;
    private String master;
    private Vector sourceFiles;
    private int currFileId;
    private int size;
    private JspCompilationContext context;
    private ErrorDispatcher err;

    /*
     * Set to true when using the JspReader on a single file where we read up
     * to the end and reset to the beginning many times.
     * (as in ParserController.figureOutJspDocument()).
     */
    private boolean singleFile;

    /*
     * Constructor.
     */
    public JspReader(JspCompilationContext ctxt,
		     String fname,
		     String encoding,
		     JarFile jarFile,
		     ErrorDispatcher err)
	    throws JasperException, FileNotFoundException, IOException {

	this(ctxt, fname, encoding,
	     JspUtil.getReader(fname, encoding, jarFile, ctxt, err),
	     err);
    }

    /*
     * Constructor.
     */
    public JspReader(JspCompilationContext ctxt,
		     String fname,
		     String encoding,
		     InputStreamReader reader,
		     ErrorDispatcher err)
	    throws JasperException, FileNotFoundException {

        this.context = ctxt;
	this.err = err;
	sourceFiles = new Vector();
	currFileId = 0;
	size = 0;
	singleFile = false;
	pushFile(fname, encoding, reader);
    }

    /*
     * @return JSP compilation context with which this JspReader is 
     * associated
     */
    JspCompilationContext getJspCompilationContext() {
        return context;
    }
    
    String getFile(int fileid) {
	return (String) sourceFiles.elementAt(fileid);
    }
	
    boolean hasMoreInput() throws JasperException {
	if (current.cursor >= current.stream.length) {
            if (singleFile) return false; 
	    while (popFile()) {
		if (current.cursor < current.stream.length) return true;
	    }
	    return false;
	}
	return true;
    }
    
    int nextChar() throws JasperException {
	if (!hasMoreInput())
	    return -1;
	
	int ch = current.stream[current.cursor];

	current.cursor++;
	
	if (ch == '\n') {
	    current.line++;
	    current.col = 0;
	} else {
	    current.col++;
	}
	return ch;
    }

    /**
     * Back up the current cursor by one char, assumes current.cursor > 0,
     * and that the char to be pushed back is not '\n'.
     */
    void pushChar() {
	current.cursor--;
	current.col--;
    }

    String getText(Mark start, Mark stop) throws JasperException {
	Mark oldstart = mark();
	reset(start);
	CharArrayWriter caw = new CharArrayWriter();
	while (!stop.equals(mark()))
	    caw.write(nextChar());
	caw.close();
	reset(oldstart);
	return caw.toString();
    }

    int peekChar() throws JasperException {
        if (!hasMoreInput())
            return -1;
	return current.stream[current.cursor];
    }

    Mark mark() {
	return new Mark(current);
    }

    void reset(Mark mark) {
	current = new Mark(mark);
    }

    boolean matchesIgnoreCase(String string) throws JasperException {
	Mark mark = mark();
	int ch = 0;
	int i = 0;
	do {
	    ch = nextChar();
	    if (Character.toLowerCase((char) ch) != string.charAt(i++)) {
		reset(mark);
		return false;
	    }
	} while (i < string.length());
	reset(mark);
	return true;
    }

    /**
     * search the stream for a match to a string
     * @param string The string to match
     * @return <strong>true</strong> is one is found, the current position
     *         in stream is positioned after the search string, <strong>
     *	       false</strong> otherwise, position in stream unchanged.
     */
    boolean matches(String string) throws JasperException {
	Mark mark = mark();
	int ch = 0;
	int i = 0;
	do {
	    ch = nextChar();
	    if (((char) ch) != string.charAt(i++)) {
		reset(mark);
		return false;
	    }
	} while (i < string.length());
	return true;
    }

    boolean matchesETag(String tagName) throws JasperException {
	Mark mark = mark();

	if (!matches("</" + tagName))
	    return false;
	skipSpaces();
	if (nextChar() == '>')
	    return true;

	reset(mark);
	return false;
    }

    boolean matchesETagWithoutLessThan(String tagName)
        throws JasperException
    {
       Mark mark = mark();

       if (!matches("/" + tagName))
           return false;
       skipSpaces();
       if (nextChar() == '>')
           return true;

       reset(mark);
       return false;
    }


    /**
     * Looks ahead to see if there are optional spaces followed by
     * the given String.  If so, true is returned and those spaces and
     * characters are skipped.  If not, false is returned and the
     * position is restored to where we were before.
     */
    boolean matchesOptionalSpacesFollowedBy( String s )
	throws JasperException
    {
        Mark mark = mark();

        skipSpaces();
        boolean result = matches( s );
        if( !result ) {
            reset( mark );
        }

        return result;
    }

    int skipSpaces() throws JasperException {
	int i = 0;
	while (hasMoreInput() && isSpace()) {
	    i++;
	    nextChar();
	}
	return i;
    }

    /**
     * Skip until the given string is matched in the stream.
     * When returned, the context is positioned past the end of the match.
     *
     * @param s The String to match.
     * @return A non-null <code>Mark</code> instance (positioned immediately
     *         before the search string) if found, <strong>null</strong>
     *         otherwise.
     */
    Mark skipUntil(String limit) throws JasperException {
        Mark ret = null;
        int limlen = limit.length();
        int ch;

    skip:
        for (ret = mark(), ch = nextChar() ; ch != -1 ;
                 ret = mark(), ch = nextChar()) {
            if (ch == limit.charAt(0)) {
                Mark restart = mark();
                for (int i = 1 ; i < limlen ; i++) {
                    if (peekChar() == limit.charAt(i))
                        nextChar();
                    else {
                        reset(restart);
                        continue skip;
                    }
                }
                return ret;
            }
        }
        return null;
    }

    /**
     * Skip until the given string is matched in the stream, but ignoring
     * chars initially escaped by a '\'.
     * When returned, the context is positioned past the end of the match.
     *
     * @param s The String to match.
     * @return A non-null <code>Mark</code> instance (positioned immediately
     *         before the search string) if found, <strong>null</strong>
     *         otherwise.
     */
    Mark skipUntilIgnoreEsc(String limit) throws JasperException {
	Mark ret = null;
	int limlen = limit.length();
	int ch;
	int prev = 'x';	// Doesn't matter
	
    skip:
	for (ret = mark(), ch = nextChar() ; ch != -1 ;
	         ret = mark(), prev = ch, ch = nextChar()) {	    
	    if (ch == '\\' && prev == '\\') {
		ch = 0;		// Double \ is not an escape char anymore
	    }
	    else if (ch == limit.charAt(0) && prev != '\\') {
		for (int i = 1 ; i < limlen ; i++) {
		    if (peekChar() == limit.charAt(i))
			nextChar();
		    else
			continue skip;
		}
		return ret;
	    }
	}
	return null;
    }
    
    /**
     * Skip until the given end tag is matched in the stream.
     * When returned, the context is positioned past the end of the tag.
     *
     * @param tag The name of the tag whose ETag (</tag>) to match.
     * @return A non-null <code>Mark</code> instance (positioned immediately
     *	       before the ETag) if found, <strong>null</strong> otherwise.
     */
    Mark skipUntilETag(String tag) throws JasperException {
	Mark ret = skipUntil("</" + tag);
	if (ret != null) {
	    skipSpaces();
	    if (nextChar() != '>')
		ret = null;
	}
	return ret;
    }

    final boolean isSpace() throws JasperException {
        // Note: If this logic changes, also update Node.TemplateText.rtrim()
	return peekChar() <= ' ';
    }

    /**
     * Parse a space delimited token.
     * If quoted the token will consume all characters up to a matching quote,
     * otherwise, it consumes up to the first delimiter character.
     *
     * @param quoted If <strong>true</strong> accept quoted strings.
     */
    String parseToken(boolean quoted) throws JasperException {
	StringBuffer stringBuffer = new StringBuffer();
	skipSpaces();
	stringBuffer.setLength(0);
	
        if (!hasMoreInput()) {
            return "";
        }

	int ch = peekChar();
	
	if (quoted) {
	    if (ch == '"' || ch == '\'') {

		char endQuote = ch == '"' ? '"' : '\'';
		// Consume the open quote: 
		ch = nextChar();
		for (ch = nextChar(); ch != -1 && ch != endQuote;
		         ch = nextChar()) {
		    if (ch == '\\') 
			ch = nextChar();
		    stringBuffer.append((char) ch);
		}
		// Check end of quote, skip closing quote:
		if (ch == -1) {
		    err.jspError(mark(), "jsp.error.quotes.unterminated");
		}
	    } else {
		err.jspError(mark(), "jsp.error.attr.quoted");
	    }
	} else {
	    if (!isDelimiter()) {
		// Read value until delimiter is found:
		do {
		    ch = nextChar();
		    // Take care of the quoting here.
		    if (ch == '\\') {
			if (peekChar() == '"' || peekChar() == '\'' ||
			       peekChar() == '>' || peekChar() == '%')
			    ch = nextChar();
		    }
		    stringBuffer.append((char) ch);
		} while (!isDelimiter());
	    }
	}

	return stringBuffer.toString();
    }

    void setSingleFile(boolean val) {
        singleFile = val;
    }

    /**
     * Gets the URL for the given path name.
     *
     * @param path Path name
     *
     * @return URL for the given path name.
     *
     * @exception MalformedURLException if the path name is not given in 
     * the correct form
     */
    URL getResource(String path) throws MalformedURLException {
        return context.getResource(path);
    }

    /**
     * Parse utils - Is current character a token delimiter ?
     * Delimiters are currently defined to be =, &gt;, &lt;, ", and ' or any
     * any space character as defined by <code>isSpace</code>.
     *
     * @return A boolean.
     */
    private boolean isDelimiter() throws JasperException {
	if (! isSpace()) {
	    int ch = peekChar();
	    // Look for a single-char work delimiter:
	    if (ch == '=' || ch == '>' || ch == '"' || ch == '\''
		    || ch == '/') {
		return true;
	    }
	    // Look for an end-of-comment or end-of-tag:		
	    if (ch == '-') {
		Mark mark = mark();
		if (((ch = nextChar()) == '>')
		        || ((ch == '-') && (nextChar() == '>'))) {
		    reset(mark);
		    return true;
		} else {
		    reset(mark);
		    return false;
		}
	    }
	    return false;
	} else {
	    return true;
	}
    }

    /**
     * Register a new source file.
     * This method is used to implement file inclusion. Each included file
     * gets a unique identifier (which is the index in the array of source
     * files).
     *
     * @return The index of the now registered file.
     */
    private int registerSourceFile(String file) {
        if (sourceFiles.contains(file))
            return -1;
	sourceFiles.addElement(file);
	this.size++;
	return sourceFiles.size() - 1;
    }
    

    /**
     * Unregister the source file.
     * This method is used to implement file inclusion. Each included file
     * gets a uniq identifier (which is the index in the array of source
     * files).
     *
     * @return The index of the now registered file.
     */
    private int unregisterSourceFile(String file) {
        if (!sourceFiles.contains(file))
            return -1;
	sourceFiles.removeElement(file);
	this.size--;
	return sourceFiles.size() - 1;
    }

    /**
     * Push a file (and its associated Stream) on the file stack.  THe
     * current position in the current file is remembered.
     */
    private void pushFile(String file, String encoding, 
			   InputStreamReader reader) 
	        throws JasperException, FileNotFoundException {

	// Register the file
	String longName = file;

	int fileid = registerSourceFile(longName);

        if (fileid == -1) {
            err.jspError("jsp.error.file.already.registered", file);
	}

	currFileId = fileid;

	try {
	    CharArrayWriter caw = new CharArrayWriter();
	    char buf[] = new char[1024];
	    for (int i = 0 ; (i = reader.read(buf)) != -1 ;)
		caw.write(buf, 0, i);
	    caw.close();
	    if (current == null) {
		current = new Mark(this, caw.toCharArray(), fileid, 
				   getFile(fileid), master, encoding);
	    } else {
		current.pushStream(caw.toCharArray(), fileid, getFile(fileid),
				   longName, encoding);
	    }
	} catch (Throwable ex) {
	    log.error("Exception parsing file ", ex);
	    // Pop state being constructed:
	    popFile();
	    err.jspError("jsp.error.file.cannot.read", file);
	} finally {
	    if (reader != null) {
		try {
		    reader.close();
		} catch (Exception any) {}
	    }
	}
    }

    /**
     * Pop a file from the file stack.  The field "current" is retored
     * to the value to point to the previous files, if any, and is set
     * to null otherwise.
     * @return true is there is a previous file on the stck.
     *         false otherwise.
     */
    private boolean popFile() throws JasperException {

	// Is stack created ? (will happen if the Jsp file we're looking at is
	// missing.
	if (current == null || currFileId < 0) {
	    return false;
	}

	// Restore parser state:
	String fName = getFile(currFileId);
	currFileId = unregisterSourceFile(fName);
	if (currFileId < -1) {
	    err.jspError("jsp.error.file.not.registered", fName);
	}

	Mark previous = current.popStream();
	if (previous != null) {
	    master = current.baseDir;
	    current = previous;
	    return true;
	}
	// Note that although the current file is undefined here, "current"
	// is not set to null just for convience, for it maybe used to
	// set the current (undefined) position.
	return false;
    }
}

